1. Field of the Invention
The present invention relates to a boat provided with an electric steering device that steers a boat propulsion unit of an outboard motor or the like by an electric signal supplied from an operator's seat.
2. Description of the Related Art
JP-B-2959044 discloses a conventional boat of this type. According to JP-B-2959044, a boat propulsion unit (outboard motor) provided with an engine and a propeller or the like for traveling is disposed on the outside of a hull, a steering motor for turning the outboard motor in the horizontal direction is disposed in a joint between the hull and the outboard motor, and the steering motor and a steering unit as a boat propulsion unit operation controller disposed in a steering motor and an operator's seat are connected by a signal cable (electric wire) that is capable of two way transmission of signals. A turning angle sensor is disposed in the steering unit, and the steering motor turns to steer the outboard motor based on a turning direction and a turning angle of the steering unit detected by the turning angle sensor.
However, in the invention described in JP-B-2959044, when a steering motor output to perform steering is smaller than a steering load due to a reduced battery charge amount, steering may not be able to be performed sufficiently. For this reason, it is hoped to achieve a control that can perform steering effectively.
In addition, in a boat in which a plurality of outboard motors are provided, steering loads on the right and left outboard motors are different at the time of turning. Also, a steering load changes depending on the boat on which the outboard motors are mounted and depending on a traveling condition. In the steering device for a boat in JP-B-2959044 or in other conventional steering devices for a boat, electric power is generated by each boat propulsion unit, and is supplied to a support device, a PTT (power trim and tilt device), an engine starter, a steering device, and so on. However, there maybe a response delay due to insufficient electric power for steering or a faulty engine start due to a reduced battery voltage under specific conditions such as a heavy load, a trim in condition, high speed traveling, and abrupt steering.